[Moon-Net] 2M antenna matching Data

Robert Nezelek rnezele1 at rochester.rr.com
Mon Nov 7 19:40:37 CET 2016



-----Original Message-----
From: moon-net-bounces at mailman.pe1itr.com
[mailto:moon-net-bounces at mailman.pe1itr.com] On Behalf Of Curt Nixon
Sent: Monday, November 7, 2016 11:17 AM
To: moon-net at mailman.pe1itr.com
Subject: [Moon-Net] 2M antenna matching Data

Good Morning All:

So, I am at the edge of my personal experience database here!  I had a 
brand new K1FO built by Directive Systems and I built a second one to 
match.  When I adjusted the Driven element Tee, all I had was an SWR 
analyzer....and not a fancy one.

So trying to figure out what is wrong with this system, I now have a 
simple vector impedance analyzer--I have collected sweeps on most of the 
components now but am out of my depth at interperting the results.  
Hopefully the group can enlighten me.

Here is the data taken from each antenna mounted on the cross boom using 
the jumpers as they are installed except dropping the ends to the 
analyzer well below the antennas.

Antenna data taken with Times T100 and CzCube software utility

Value /    Antenna ID
     S            N
F    144.700*        144.775*
ZL    52.12+J6.70        51.25+J4.11
RL    -23.35            -27.54
G    0.02 +J0.07        0.01+J0.04
angle    70.8            70.7

* Data at F= low point in SWR/RL Value
With jumpers arranged as they will be in use




F    144.1            144.1
ZL    54.34+J9.22        56.43+J5.57
RL    -20.26            -22.05
G    0.05+J0.08        0.01+J0.05
angle    59.7            37.9


Clearly they are not the same...and both indicate they are tuned high.  
But I still have some questions on what I should be aiming for as far as 
Return Loss and how important are the other numbers. I did not think to 
do both of them using the same jumper---but will do that when I start to 
adjust them.

I did measure the divider alone with 50 ohm terminations on each end and 
it  shows 50.02 ohms and RL of -31dB but was not in the data above.

I also looked at the jumpers disconnected from the antennas and see some 
differences between the ones I built and the ones that came from an 
older 4x array I purchased that was running well when taken down.  But 
for the above data both were similar in RL and length using the R+Jx 
crossover point.

So..how close should the two yagis be?  What values should I be using to 
determine if they are adjusted properly?

Thanks a bunch---and I would be happy to take this discussion off the 
board unless it may help others going thru the same thing.

Curt
KU8L
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